Patches to be applied to the skin for the purpose of, e.g., protecting the affected part and adhesive preparations to be applied to a surface of the skin of a mammal for the purpose of percutaneously administering a drug to the mammal have hitherto been developed.
Such a patch generally includes a backing, a pressure-sensitive adhesive layer formed on at least one side of the backing, and a release liner which protects the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer. When such a patch is used, the release liner is peeled off. In some patches, the release liner has a weakening line formed therein so as to assist the removal of the release liner. The user utilizes the weakening line for securing a hold for removing the release liner. Namely, the user pinches areas around the weakening line with fingers to remove the release liner.
WO 00/69422 pamphlet describes a patch having a release liner, in which the release liner can be made easily peelable by forming a weakening line of a given shape in a surface of the release liner. However, this patch has the following drawback. Namely, the pressure-sensitive adhesive layer may protrude from or flow out through the weakening line and adhere to inner surfaces of the package in which the patch is placed. There is hence a possibility that it might become difficult to take the patch out of the package or the pressure-sensitive adhesive layer adheres to the hand of the user to give an uncomfortable feeling.
Examples of the techniques for avoiding the adhesion of the pressure-sensitive adhesive layer to inner surfaces of the package include the following. JP-T-10-511330 (the term “JP-T” as used herein means a published Japanese translation of a PCT patent application) discloses a patch package structure in which a patch having a release liner is placed in a blister pack and sealed with a sheet material. A weakening line has been formed in a surface of the release liner of the patch in order to assist the removal of the release liner. This patch package structure disclosed has a given shape so that even when the pressure-sensitive adhesive layer protrudes from an edge of the patch, the adhesive is less apt to adhere to the inner surfaces of the package.
However, since the weakening line of the patch can freely come into contact with the sheet material in this package structure, there is a fear that when the pressure-sensitive adhesive layer protrudes from the weakening line, then the adhesive may adhere to an inner surface of the package to make it difficult to take out the patch or may adhere to the hand of the user to give an uncomfortable feeling.
JP-A-2008-188414 discloses a patch package structure in which a patch having a release liner is disposed so that a weakening line formed in a surface of the release liner faces a planar sheet material. However, even in this patch package structure, the weakening line may still come into contact with the sheet material. There are hence cases where some degree of care is necessary for avoiding the protrusion of the pressure-sensitive adhesive layer through the weakening line.
Recently, soft pressure-sensitive adhesive layers such as pressure-sensitive adhesive layers holding a large amount of a liquid component therein tend to be employed for the purpose of obtaining a soft wear feeling during wear of the patch or reducing the skin irritation caused by separation of the horny layer upon stripping of the patch. With regard to adhesive preparations in which the pressure-sensitive adhesive layer contains a drug, a pressure-sensitive adhesive layer having a larger thickness has been frequently employed in recent adhesive preparations so that the pressure-sensitive adhesive layer can hold a large amount of a drug. In such cases where the pressure-sensitive adhesive layer contains a large amount of a liquid component or the pressure-sensitive adhesive layer is thick, the problem described above is apt to be actualized. There is hence a strong desire for a patch package structure in which a patch can be easily taken out of the package and can be comfortably used.